Under each function similar to above; there is a commented line below it which includes code to use the Steam Browser. You must comment the Integrated Browser code, and uncomment the Steam Browser code.
Currently; the integrated browser mode works by utilizing a library developed by Facepunch for Garry's Mod. Developers do not have access to actually change / update code in that library.
If you enable the Integrated Browser; and notice that certain websites are appearing blank; then you will need to either change the URL; or disable the integrated browser.
This is due to the fact that the provided library by Facepunch is extremely outdated and is based on Chromium v22 which is extremely outdated and does not recognize code used on websites. As of writing this; the current version of Chromium is v89.
Until Facepunch actually updates Chromium for Garry's Mod; this is the only solution.